In short:
- You need the LocalFiles Editor plugin (https://piwigo.org/ext/extension_view.php?eid=144)
- You must get recaptcha v2 keys for your domain
(https://www.google.com/recaptcha/admin#list)
- You must define three config variables:
The first one changes the function, which verifies the users password
The second one is the "Website Key" (or similar).
The third and last one is the "Secret key".
Please put the two keys inside ' as shown below: